13. 英国《自然》杂志报道,科学家最近研制成了以锶原子做钟摆的“光格钟”,成了世界上最精确的钟。已知一种锶原子的相对原子质量为88,其质子数是38,则一个这种锶原子中含有的微粒总数为 ( )
A.38 B.50 C.88 D.126
12. 下列各反应中,各物质之间的质量比为1∶1∶2的是······································· ( )
A.H2 +Cl22HCl
B.N2
+O2
2NO
C.S + O2SO2
D.Fe +
S
FeS
11. 下列化学方程式书写完全正确的是··································································· ( )
A.2H2O = 2H2 + O2 B.Mg + O2MgO2
C.4Fe + 3O22Fe2O3 D.CO2 + Ca(OH)2 = CaCO3↓+ H2O
10. 某纯净物在受热时发生分解反应生成水、二氧化碳和氨气(NH3)三种物质。下列对该物质的推断中,错误的是······················································································································· ( )
A.该物质一定是化合物
B.该物质是由氢、氧、氮、碳四种元素组成的
C.该物质是由水分子、二氧化碳分子、氨分子构成的
D.该物质中氮、氢、碳、氧元素的质量比可能是14∶5∶12∶48
9. 金属元素M只有一种化合价,其氧化物的化学式为MO,则下列化学式中错误的是( )
A.MCl2 B.MCO3 C.MSO4 D. MOH
8. 已知,若有m个水分子生成,则参加反应的氧原子的个数为··························· ( )
A.m/2 B.m C.3m/2 D.2m
7. 下列有关实验现象的描述正确的是··································································· ( )
A.碳在氧气中燃烧,生成白烟
B.铁丝在空气中燃烧,发出耀眼的强光,生成黑色固体
C.硫在空气中燃烧,生成一种有刺激性气味的气体
D.红磷在空气中燃烧,生成五氧化二磷
6. 我国的淡水资源非常匮乏,同学们在生活中要注意节约用水,保护水资源。下列是某附属中学初三(1)班的郑灿同学周日一天的用水情况,其中我们应该提倡的是················································· ( )
①早上间歇用水刷牙 ②中午淘米淘菜的水浇花
③吃饭后不间断用水洗碗 ④下午洗衣服的水用来冲厕所
⑤晚上洗澡打香皂时让水龙头继续流水
A.①②④ B.②③⑤ C.③④⑤ D.②④⑤
5. 自然界中发生的下列现象不是由于空气污染造成的是······································· ( )
A.酸雨危害 B.海洋赤潮 C.光化学烟雾 D.臭氧层空洞
4. 空气中氧气和氮气的体积比约为······································································ ( )
A.1︰1 B.1︰5 C.1︰4 D.1︰2
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